← Back to Sessions

Vertical-Slice Ocean Tomography Using CTBTO Hydrophones

Description: 

Monitoring the warming of the global ocean remains a challenging sampling problem because the observational coverage is limited. Seismic ocean thermometry (SOT) uses T waves from repeating earthquakes to infer large-scale averaged ocean temperature changes complementing existing in situ point measurements. We have previously used a T-wave station at the Diego Garcia atoll to demonstrate the merits of SOT. Compared to those land-based seismometers, CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organization) hydrophones can record T waves with much lower noise levels and therefore allow us to use T waves from small repeating earthquakes (magnitude < 4.0) to improve the temporal resolution of the inferred temperature change. In this study, two CTBTO hydrophones in the Indian Ocean are used to capture ocean signals that include decadal warming, seasonal variations, equatorial waves, and mesoscale eddies. Compared to our previous single-frequency measurement scheme, here we also use the relationship between frequency-dependent T-wave travel time changes and depth-dependent temperature changes to conduct depth-slice tomography. The tomography results are consistent with our understanding of ocean dynamics and predictions based on the ECCO (Estimating the Circulation and Climate of the Ocean) state estimate. This application demonstrates the great advantage of hydrophone stations for applying SOT globally, especially in regions with low seismicity levels.

Session: Monitoring Climate Change With Seismology

Type: Oral

Date: 4/18/2023

Presentation Time: 10:15 AM (local time)

Presenting Author: Wenbo Wu

Student Presenter: No

Invited Presentation: 

Authors